> supported roughly through the release of 3.n+1-rc1.
Actually, non-longterm 3.n series are guaranteed to get at least one stable release after 3.(n+1) final has been released. This so that if anyone else wants to continue to maintain it (like your distro maintainer), they only have to slug through the stable updates of later kernels to find patches to backport.
Usually that means that the last 3.n.x stable release are made simultaneously with 3.(n+1).1, though sometime it is made between 3.(n+1) and 3.(n+1).1, and sometimes it is made simultaneously with 3.(n+1).2.